NMS Core: 1. A computer-controlled, motorized upright fluorescence microscope (Zeiss Axioimager), with piezo-controlled stage and microscanning CCD camera. This microscope is well-equipped for Array Tomography data acquisition. 2. An inverted, laser scanning confocal microscope with spectral imaging capability (Zeiss LSM510 Meta) and an environmental control chamber for time-lapse imaging of live cells. 3. Two upright two-photon microscopes on a single large optical table, sharing a pair of Ti:sapphire femtosecond pulsed lasers. Both microscopes are equipped for simultaneous two-photon imaging and twophoton photoactivation. Configurable table optics also allow for simultaenous imaging at dual wavelengths. a. One microscope is designed for in vivo imaging (Ultima IV, Prairie Technologies, Middleton, Wl). b. The other microscope is designed for tissue slice imaging (Ultima XY, Prairie Technologi